1. Field of the Invention
The present invention relates to a printed circuit that connects a pre-amplifier circuit to a head of a hard disk drive.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads can magnetize and sense the magnetic fields of the disk to write and read data, respectively. The heads each have an air bearing surface that cooperates with a flow of air generated by the rotating disk to create an air bearing. The air bearing prevents mechanical wear between the head and the disk.
To facilitate formation of the air bearing the head is typically attached to a gimbal that pivots about a flexure arm. The flexure arm is cantilevered from the end of an actuator arm. The actuator arm has a voice coil motor that moves the heads across the surfaces of the disks.
The output signals of the heads are amplified by a pre-amplifier circuit of the drive. The pre-amplifier circuit is connected to the heads by wires and/or flexible circuits that are attached to the flexures. The flexible circuits have conductive traces that connect designated bond pads of the heads to corresponding lines of a pre-amplifier circuit assembly.
Hard disk drives have been conventionally assembled to have a head (“Dn head”) on a top surface of a disk and a head (“Up head”) of a bottom surface of the disk. FIG. 1 schematically shows Dn 1 and Up 2 heads relative to a disk 3. Each head 1 and 2 has a plurality of bond pads 4 labeled H, W−, W+, R−, R+ and G. The W and R pads are connected to the write and read elements of the heads, respectively. The G pad is ground and the H pad is connected to a fly on demand element of the head. It is desirable to have the head pads aligned when assembled in a disk drive.
The heads are typically fabricated in wafer form. Each wafer has both Up and Dn heads. The Up and Dn heads are fabricated to have mirror image bond pad patterns so that when the Dn heads are assembled the pads arrangements are the same as shown in FIG. 1.
There have been developed disk drives that use only a single head. To reduce cost and the complexity of inventory the heads are fabricated on wafers so that all the heads have the same bond pad pattern. When such heads are used, the bond pad pattern of the Up heads become misaligned with the corresponding bond patterns of the Dn heads 1 as shown in FIG. 2. The bond pads of the heads and or pre-amplifier circuit assembly can be changed, but this would increase process time and cost. It would be desirable to convert a head from a single head wafer into a Up head without changing the bond pad arrangements of the head or pre-amplifier circuit.